Fig. 4From: Stereoscopic facial imaging for pain assessment using rotational offset microlens arrays based structured illuminationa Contour lines of the Mahalanobis distance in 2D space. b Distance features for pain rating. x1, x2: from eyebrow to mouth; x3, x4: from eyebrow to eye; x5: mouth height; x6: mouth width; x7, x8: from eye to mouthBack to article page